Induction-furnace coil



March 10, 1931. r. H. BRACE 1,795,327

INDUCTION FURNACE COIL Filed Aug. 14,1929

NLTOR 4. porzerliB/ace.

Patented Mar. 10, 1931 UNITED STATES PATENT OFFICE PORTER H. BRACE, OF FOREST HILLS, PENNSYLVANIA, ASSIGNOR. TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA INDUCTION-FURNACE c011.

Application 'iiled August 14, 1929. Serial No. 885,765.

My invention relates to electric furnaces and particularly to electric induction furnaces of the surrounded-pool type.

An object of my invention is to provide a relatively simple and highly eifici-ent coil structure for an induction furnace of relatively large size.

Another object of my invention is to provide an induction coil, for a relatively large furnace embodying a crucible, that shall em body inherent means for maintainingitself in close operative engagement with the outside of the crucible.

Another object of my invention is to provide a furnace coil having one or more relatively short portions of greater resiliency than the other portions thereof, in combination with auxiliary resilient means operating to maintain the coil in close operative engagement with the outside of a crucible, irrespective of the expansion and contraction thereof, incident to heating and cooling.

In practicing my invention, I. provide a refractory lining or crucible, a casing surrounding the same and spaced therefrom, which casing may be provided with means for permitting of tilting the crucible, and a helically wound coil having a plurality of turns, each turn having major portions extending through a predetermined path peripherally of, and in close operative engagement witl'h, the outside periphery of the crucible,-each urn having at least one relatively short portion of greater resiliency than the major portion and bowed or deformed out of the normal path of the turn. I provide also a plurality of resilient supporting or pressing means operatively engaging the relatively short portions of each turn to assist in maintaining the major portlons of each turn in close operative engagement with the outside of the crucible.

In the single sheet of'drawings,

. Figurel is a top plan view of an induction furnace embodying my invention.

Fig. 2 is a view, in vertical section, taken on the line IIII of Fig. 1.

Fig. 3 is a fragmentary view of a modlfied form of the coil structure embodying my 1nvention, and

Fig. 4 is a section, taken on the line IVIV of Fig. 3.

My invention is particularly applicable toinduction furnaces of the surrounded-pool type and of relatively large size, in which it is highly desirable, if not actually necessary, that close operative engagement be maintained between the energizing coil surrounding the crucible and the crucible itself in order that the inter-linkage: of the lines of force generated by the current-traversed energizing coil with the material in the crucible shall be a maximum.

A crucible 11 is shown as being built up 0 suitable bricks or blocks of a refractory material adapted to withstand the high temperatures of the material to be melted in the crucible. While a built-up crucible is shown, this is more particularly for illustrative purposes and I may use a crucible embodying a properly shaped mass of material, such as may be'use'd in the case of smaller crucibles.

A casing 12, which may be of metallic or of shroud 14 of electric-insulating material is located around the crucible in order to reduce the amount of granular material necessary to be used. The crucible 11 may rest on a bottom layer of the granular material 13, as is shown more particularly in Fig. 2 of the drawings.

An energizing coil 16 is provided around the crucible and embodies a substantially solid portion 17 for carrying an electric current and a tubular portion 18 for carr ing a cooling fluid. As shown in Fig. 2 o the drawings, the tubular portion 18' is separate from, or brazed or otherwise secured to, the solid portion 17.

The solid portion 17 is made in arcuate sections, shown as being four in number in Fig. 1 of the drawings, connections between the adjacent ends of the sections of the conductor 17 being effected by resilient bowed stri s 19 the ends of which are suitably inter tted with the ends of the sections of the conductor 17 and brazed therein or other-- wise secured thereto. The tubular member 18 is provided with a bowed-out or deformed portion21, which, in the case of the construction shown more particularly in Figs. 1 and 2 of'the drawings, extends radially outward from the crucible or radially lugs 23, one end of each spring engaging the rod or bar 22 and the other end engaging a lug 26 integral with the casing 12. The lugs 23 and the springs 24 extend tangentially of the coil 16 and assist the inherent resiliency of the portions 19 and 21 of the coil to maintain the conductor in close operative engagement with the crucible and more particular ly with the member 14.

' Figs. 3 and 4 showa modification in which a coil, having a plurality of turns of a conductor 31, including a solid current-con,- ducting portion and a tubular cooling fluidconducting portion, has integral relatively short portions 32 bent out of the normal path of the major portion of the turn, in

this case, downwardly from the plane of the turn. While I have shown no auxiliary resilient clamping or pressing portions, such as are shown in Fig. 1 of the drawings, it is to be understood that I may use these if necessary.

.The casing 12 may be provided with short shafts or trunnions 33 to permit of tiltably supportingthe entire furnace structure in order to effect removal of the molten material through a pouring spout 34.

No electrical connection from a supply circuit tothe coil 16 is shown, as any suitable or desired construction of such parts may be provided, in a manner well known in the art.

When an induction furnace of relatively large size is emplo ed, it is highly desirable, if not necessary, t at the inner diameter of the energizing coil be but little larger than the outside of the crucible in order to reduce the amount ofleakage flux, and hence, the radial thickness of the material 13 is made as small as possible, as is also the radial thickness of the member 14. As the crucible will expand and contract, incident to its heating and cooling, in actual use, the device embodying my invention provides a means for maintaining the inner face of each turn of the conductor in close operative engagement with the crucible or with material immediately surrounding the crucible, so

that the coil will follow the expansions and contractions of the crucible, when in use, thereby tending to prevent the development the turn or, in other words, a minorportion of each turn is deformed or bowed laterally of the turn. This provides a short portion J of greater resiliency than the other .portion of each turn and',.1n cooperation with auxihary resilient pressing or clamping means engaging the minor portions, effects following-up of the movements of the crucible by the coil during operation of the, furnace.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof,

and I desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art or are set forth in the a pended claims.

I c aim'as my invention:

11. In an electric heating device for inductively heating a mass of material, an energizing coil, a shroud of electric-insulating material operatively engaged by the coil, each turn of the coil having at least one relatively short portion deformed from the normal path of the turn, whereby each turnof the coil may follow the expansion and contraction of the shroud as it is heated or cooled while remaining in operative engagement therewith.

2.- In an electric heating device for inductively heating a mass of'material, an energizing coil surrounding said mass of materibent laterally out of the plane of thenomral path of the turn.

3. In an electric heating device for inductively heating amass of material, an energizing coil surrounding the mass of material in operative engagement therewith, each turn of the coil including a portion of greater resiliency than the other portions and extendmg through a circuitous path aside from the normal path of the turn.

4. In an electric heating device for inductively heating a mass of material, an energizing co1 l surrounding the mass of material in operativeengaiglment therewith, each turn of the coil mclu g a portion of greater re, siliency thanthe other portions and extendmg through a circuitous path aside from the normal path of the turn and resilient means operativelyengaging the turn to maintain it 5. In an electric heating device for inductively heating a mass of material, an energizing coil closely surrounding the mass of material to be heated and in operative engagement therewith, each turn of the coil including a plurality of relatively short portions of greater resiliency than the major portion of the turn and bowed out of the normal path ofthe turn, and resilient ,means at each side of the short portions for holding the major portion of the turn in operative engagement with the mass of material during expansion and contraction thereof.

6. In'an electric heating device for inductively heating a mass of material, an energizing coil surrounding the mass of material and resilient means acting substantially tangentially on the coil to maintain it in close operative engagement with the mass of material as said mass expands and contracts incident to heating and cooling.

7 In an electric heating device for inductively heating a mass of material, an energizing coil surrounding the mass of material and closely engaging the same, each turn of the coil including at least one relatively short portion bowed out of the normal path of the turn, and resilient means acting substantially tangentially on the ends of the bowed portions to maintain themajor portions of each turn in close operative engagement with the mass, irrespectlve of lts'expansion and contraction.

In testimony whereof, I have hereunto subscribed my name this 30th day of July, 1929.

PORTER H. BRAOE. 

